package com.lb;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Description: 该类是轮询算法 ，主要是处理多并发的情况下 负载均衡的轮询
 *
 * @Autor: Rolin
 * datetime: 04-26-15:54
 */
@Component
public class LoadBalancerImpl  implements LoadBalancer{

//    private AtomicInteger atomicInteger = new AtomicInteger(0);
    private AtomicInteger atomicInteger = new AtomicInteger(0);

    public final int getAndIncrement()
    {
        int current;
        int next;
        do
        {
            current = this.atomicInteger.get();
            next = current >= Integer.MAX_VALUE ? 0 : current + 1;
        } while(!this.atomicInteger.compareAndSet(current, next));
        System.out.println("*****next: "+next);
        return next;
    }

    @Override
    public ServiceInstance instance(List<ServiceInstance> serviceInstances) {
        int index = getAndIncrement() % serviceInstances.size();
        return serviceInstances.get(index);
    }
}
